Stretching 5 miles along the Mississippi River, Davenport is part of the Quad Cities metropolitan area, which also includes Bettendorf, Iowa, and Moline and Rock Island, Illinois. Principally a regional retail center, Davenport also produces machinery, agricultural goods, and food products. Davenport's Palmer College of Chiropractic is the fountainhead of that practice in the United States. The city is named for its founder, a former US Army officer who explored this bank of the river while stationed on Rock Island. The state's first railroad came here when tracks were put across the Mississippi at this point in 1854. In pre-Civil War days, Dred Scott claimed the town as his home, and John Brown provisioned here before his attack on Harpers Ferry.